using @Model `javax.enterprise.inject.Model` for JSF backing bean?

Question

I'm trying to implement JSF backing beans using CDI beans as suggested by the depreciation of @ManagedBean and it's scope annotations, but I'm struggling with the right use examples, I'm trying to implement view backing bean with @Model (javax.enterprise.inject.Model) which is @Named @RequestScoped.

I found this question but it's using a ViewScope bean, how would I implement the same functionality with RequestScoped (Preferably @Model), What is best practice use of @Model in general?

Edit 1: I tried creating a new Product in the EditProduct PostConstruct:

@Model
public class EditProduct {

    private Product product; // +getter +setter

    @Inject
    private ProductService productService;

    @PostConstruct
    public void init(){
        product = new Product();        
    }
    public String save() {
        productService.save(product);
        return "/products?faces-redirect=true";
    }

    // ...
}

and then setting the product via

<f:viewParameter name="product-id" target="#{editProduct.product}"
converter="#{productConverter}" />

it's working but I'm looking for a best practice.

Answer 1

A request scoped backing bean is meant to keep the application memory footprint as low as possible hence using them for supporting views with @Model annotation makes a lot of sense, the draw back is having to reach for the persistence data storage on every request that deals with data so a best use case for @Model bean is:

Basically every thing. things like:

1. Events handling for JSF pages
2. Lazy loading of data
3. Validation and converting and other code execution
4. ETC.... yes every thing else

Those things are easily done best in request scoped beans, but then what are the roles of other beans?

In simplistic terms we can assume:

1. @ViewScoped to support data heavy pages where user edits data with many interactions and each interaction is a request but hitting the database for each one will be costly.

2. @SessionScoped for session data, authentication, credentials and configuration for the user.

3. @ApplicationScoped the state-full singleton of CDI.

.... each other scope has it's uses, but for a good web application @Model should be the default and the others has specific uses cases.